In the field of personal mobile devices such as laptop computers, tablet computers, and smart phones, proximity sensors are used to sense hover events. Hover events may include no touch, close proximity positioning of parts of the user's body or other objects (e.g., a stylus held by the user), near an external surface of the device. Typically, such proximity sensors are designed to detect an external object that is located outside the near field detection capability of a touch sensor (e.g., those used in a typical touch screen display such as found in an iPhone™ device by Apple Inc., of Cupertino Calif.). In one instance, the proximity sensor includes an infrared (IR) emitter and a counterpart IR detector that are controlled and sampled by proximity sensor circuitry integrated in the housing of the mobile device. Emitted infrared radiation is scattered by the external “target” object, and then detected and analyzed to infer that an external object is (or is not) close to the exterior surface of the device.
A personal mobile device may also use an ambient light sensor (ALS) to sense a brightness or intensity of ambient visible light. The ALS may include an ambient light detector that is sampled by ALS circuitry integrated in the housing of the mobile device. The ambient light level detected may be used to adjust a display brightness.